Water-based coating system with improved adhesion to a wide range of coated and uncoated substrates including muffler grade stainless steel

Abstract

The present invention provides a water-based coating system that can be used to form a durable, abrasion resistant, tough, protective coating on a wide range of substrates. The coating system advantageously has excellent adhesion properties and can be directly coated onto stainless steel surfaces without requiring an intervening primer layer. Primer layers or other types of coatings can be used in combination with the coating system of the present invention if desired, however. The coating system is particularly effective for protecting metal-containing substrates such as intermodal, refrigerated cargo containers. The resultant coatings are flexible and impact resistant. Being water-based, the coating compositions have lower VOC emissions and less residual odor than solvent-based compositions.

What is claimed is: 
     
       1. A method of coating a cargo container, comprising the steps of:
 providing a cargo container or one or more components thereof, wherein the cargo container conforms to ISO R-668, and wherein at least a portion of an exposed stainless steel surface of the cargo container or one or more components thereof includes weathering steel; 
 applying at least a coating composition to form a topcoat directly on at least the exposed stainless steel surface of the cargo container or one or more components thereof, wherein the coating composition comprises:
 an aqueous carrier; 
 at least one film forming resin in admixture with the carrier; 
 and one or more pigments comprising non-binder particles dispersed in the coating composition. 
 
 
     
     
       2. The method according to  claim 1 , wherein the coating composition comprises from about 10 to 70 weight percent of at least one film forming resin. 
     
     
       3. The method according to  claim 1 , wherein the carrier includes from about 0.3 to 15 weight percent of a co-carrier based on the total weight of the carrier. 
     
     
       4. The method according to  claim 1 , wherein at least one film forming resin is derived from an acid functional monomer, and is obtained from ingredients comprising (a) optionally, at least one aromatic reactant including pendant free radically polymerizable functionality; (b) at least one free radically polymerizable reactant having pendant acid functionality; and (c) optionally at least one other copolymerizable reactant with free radically polymerizable functionality. 
     
     
       5. The method according to  claim 1 , wherein the one or more pigments are selected from the group consisting of BaSO 4 , CaCO 3 , clay, china clay, mica, talc and mixtures thereof. 
     
     
       6. The method according to  claim 1 , wherein the pigment volume concentration of the non-binder particles in the corresponding dry coating is in the range from about 15 to 85 volume percent.